1. Field of the Invention
The present invention relates to a resonant circuit inverter having an LC series resonant circuit and a switching device for connecting the resonant circuit with periodically changing polarity to a dc voltage source, and which feeds a high voltage transformer.
2. Description of the Prior Art
A resonant circuit inverter is known from German OS No. 28 34 561 having an LC series resonant circuit comprised of a capacitor and a high voltage transformer which has a primary winding connected in series with the capacitor. A dc voltage source is connected at the input of the resonant circuit inverter. The LC series resonance circuit is connected to the poles of the dc voltage source in a manner so as to periodically alternate the polarity of the connection by means of a switch device consisting of four thyristors which are respectively bridged by four free running diodes. The polarity at the points of connection of the series resonant circuit between respective pairs of thyristors thus periodically changes and an alternating voltage is transmitted by the high voltage transformer.
The LC series resonant circuit disclosed in German OS No. 28 34 561 consists of the capacitor and a total inductance which is comprised of the sum of the leakage inductance of the high voltage transformer and a lead inductance. The required oscillation inductance is thus load-dependent and will become greater or smaller depending upon the inverter power output. Because the leakage inductance of the high voltage transformer cannot be reduced at will without the high voltage transformer becoming too large, and because the lead inductance comprises a considerable portion of the total inductance, it is difficult to achieve an oscillation inductance which is as small as necessary in the known circuit described above, particularly in the case of high inverter power outputs. This problem becomes particularly acute if the load is disposed at a spatial distance from the inverter so that a long cable is required between the inverter and the load.